(1) Field of the Invention
The present invention relates to a circuit of a display, particularly to a circuit used to test or to repair the display.
(2) Description of the Related Art
A pixel array of an active display comprises a plurality of scan lines and data lines cross with each other. Each pixel unit of the pixel array employs a thin film transistor as switch. The source electrode and gate electrode of the thin film transistor are electrically connected to the data line and scan line, respectively. When the data line or the scan line is broken, the signal cannot feed through the broken point so the image quality is worse. That is why a rescue line is employed by a display.
Referring to FIG. 1, the display 100 includes an active area 110 and a bonding area 120 on the lower substrate 101. The bonding area 120 is located at the peripheral portion of the active area 110. A sealant 130 is applied between the active area 110 and the bonding area 120 or at the peripheral portion of the active area 110 to adhere the lower substrate 101 to the upper substrate (not shown). The active area 110 is disposed with a plurality of scan lines 112, data lines 114 and thin film transistors 115. The bonding area 120 is disposed with a data driver 128 electrically connected to the data line 114, and with a scan driver 129 electrically connected to the scan line 112. Three shorting bars 122, 124, 126 disposed at one side of the bonding area 120 are electrically connected to the red, blue, green pixels and the test device (not shown) to find the defect. After testing, the shorting bars 122, 124 and 126 are cut along C-C line by laser.
In the prior art, the rescue line 116 encloses the active area 110 alone inner side of the sealant 130, but does not connect to the shorting bars 122, 124 and 126. The repairing by the rescue line 116 is described as follows. In the normal state, the rescue line 116 overlaps but electrically insulated from the data line 114 or the scan lines 112 via an insulating layer (not shown). If the data line 114 has a broken point 117, then the data driver 128 cannot transmit the data signal into the pixel unit 102 through the path A. Under the circumstances, the insulating layer of the welding point 103a and 103b is welded for conducting the rescue line 116 with the data line 114. Therefore, the data signal can transmit along the path B, that is, the signal goes to the welding point 103a, and then turn to the rescue line 116, subsequently, it goes to the welding point 103b, and is input to the thin film transistor 115 of the pixel unit 102 through the other end of the data line 114.
However, if a break point 118 is generated in the region 140 which is located outside the rescue line 116, the rescue line 116 will be out of action because the data signal cannot be transmitted into the rescue line 116. The reasons are as following:
1. Currently the rescue line 116 is disposed inside the sealant 130, so the defects, such as pad burn or lead scratch etc., occurring in the region 140 outside the rescue line 116 cannot be repaired. That causes that the display products, such as TV, are frequently discarded in the latter manufacturing process or in client end.
2. The rescue line 116 is separated from the test lines 122, 124 and 126 to reduce the utilization ratio of the substrate.